1. Field of the Invention
This invention relates to a control valve device for a hydraulic user. More specifically, the invention relates to an electrically actuated control valve that has a sliding spool to control the connection of at least one user channel with a delivery and a reservoir channel, a shutoff valve in the user channel, which shuts off a return flow from the user to the control valve and a pilot valve to actuate the shutoff valve.
2. Background Information
Control valve devices are often used to actuate single-action or double-action users. On each of the user channels that lead from the sliding spool to the user, these devices have a shutoff valve that can be controlled by a pilot control valve for the leak-free isolation of the user. The shutoff valves are check valves that open toward the user and are generally spring-loaded and can be moved by the pilot valve into the open position to make possible a return flow from the user to the sliding spool if, as a result of a corresponding deflection of the sliding spool, the user channel is in communication with the reservoir channel. In this case, the pilot valves are also spring-loaded check valves and can be actuated by an actuator element, e.g., an actuator pin, to move them into the open position. In the open position, a connection is created between the control pressure compartment of the shutoff valve, which is in communication with the user and the reservoir channel so that the shutoff valve is moved into the open position by the pressure of the user. This makes possible a flow of hydraulic fluid from the user via the open shutoff valve and the sliding spool to the reservoir.
DE-OS 20 32 107 describes a similar control valve device of the prior art with a mechanically actuated control valve that is a sliding spool. In this device, the pilot control valves can be actuated by actuator pins moved into the open position. The actuator pins are in communication with diagonal, conical-shaped control surfaces formed on the sliding spool. When there is an axial deflection of the sliding spool, the pilot control valve can thus be opened by the actuator pin. With a mechanical actuation of the pilot control valves by a diagonal control surface formed on the sliding spool, a transverse force is exerted on the actuator pin, which in turn produces friction. As a result, the control valve device of this type is sluggish and subject to wear caused by friction. Consequently, with a control valve device of this type, a high actuation force is required to move the sliding spool and to actuate the pilot control valve.
The object of this invention is to make available a control valve device of the type described above with an electrically actuated control valve, which has a low actuation force to move the sliding spool and to actuate the pilot control valve.